Self-calibrating resistive flexure sensor

ABSTRACT

A variable resistance flexure sensor, and a system and method of controlling an appliance using a variable resistance flexure sensor are provided. The sensor can include a substrate having a flexible portion and a non-flexible portion. A plurality of electrically resistive elements, such as a first resistive element and a second resistive element, can be disposed on the substrate where at least one resistive element is exclusively within the non-flexible portion of the substrate and at least one resistive element is within the flexible portion of the substrate. The resistive element within the non-flexible portion of the substrate can act as a reference resistance for the flexure sensor and can be used as, or as part of, a biasing network for the electrically resistive element within the flexible portion of the substrate. The flexure sensor can be used within an appliance to detect various conditions such as temperature, moisture, etc.

FIELD OF THE INVENTION

The present subject matter relates generally to a self-calibratingresistive flexure sensor, and more particularly to, a method and systemto improve appliance control using the self-calibrating resistiveflexure sensor.

BACKGROUND OF THE INVENTION

Flexible resistive sensors, such as flexure sensors, flex sensors,bending sensors, strain gages, etc., can be used to measure variousconditions such as temperature, moisture, air flow, mechanical stress,etc. A variable resistance element can be provided on a flexiblesubstrate that changes shape and/or dimensions based on the conditionbeing measured. More specifically, an electrical resistance of theresistive element is variable corresponding to a change in flexure ofthe flexible substrate. The flexure of the substrate, and thus theresistive element, is caused by the physical quantity to be measuredwith the sensor. For example, a flexure sensor can be placed in an airpathway (duct, pipe, tube) and used to measure the air flow rate(velocity) within the pathway.

Conventionally, the electrically resistive elements of flexure sensorsare manufactured using a printing technique such as screen printing orby a metal deposition technique such as sputtering. However, theelectrically resistive elements formed using these techniques can haveinconsistent properties due to a variety of factors such as stencilaccuracy, material thickness, and material composition. These factorscan vary from day to day during the manufacturing process. Therefore,the response (transfer function) of any device that utilizes a flexuresensor having resistive elements created using these techniques are nottypically uniform (consistent) for all sensors but rather unique foreach device. In other words, a device using a resistive flexure sensorneeds a way to be “calibrated” as a system to compensate for thegenerally loose tolerances of the sensor.

In a conventional approach, the resistive element of a flexure sensor iscoupled to a biasing/scaling network configured to provide apredetermined amount of current through the resistive sensor element soas to produce a flexure-dependent variable voltage within some desiredrange. One or more fixed-value resistors are generally used to bias theresistive element of the flexure sensor, including a common resistordivider or Wheatstone Bridge configuration. However, changes in ambienttemperature in the system can non-uniformly affect the resistanceresponse of the resistive element of the flexure sensor and the biasingnetwork because the temperature coefficients of the resistive flexuresensing element and the biasing network are not exactly the same.Therefore, calibration of the sensor is difficult because the biasingnetwork cannot adequately compensate for the non-uniform variableresponse of the resistive element of the sensor.

Thus, a need exists for a flexure sensor having an improved biasingnetwork for self-calibrating the flexure sensor and cancelling-out theeffects of part-to-part variation and temperature-dependent shifts.

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention will be set forth in part in thefollowing description, or may be apparent from the description, or maybe learned through practice of the invention.

One exemplary aspect of the present disclosure is directed to a flexuresensing device. The flexure sensing device includes a substrate having aflexible portion and a non-flexible portion. The flexure sensing devicefurther includes a first resistive element formed on or within theflexible portion of the substrate. The first resistive element has avariable electrical resistance dependent on a change in flexure of theflexible portion of the substrate. The flexure sensing device furtherincludes a second resistive element formed on or within the non-flexibleportion of the substrate. The second resistive element provides areference resistance for the flexure sensing device.

Another exemplary aspect of the present disclosure is directed to amethod of manufacturing a flexure sensing device. The method includesdepositing first and second resistive elements on or within a flexiblesubstrate. The first resistive element has a variable electricalresistance dependent on a change in flexure of the flexible substrate.The method further includes forming a non-flexible portion of thesubstrate such that the second resistive element is disposed on orwithin the non-flexible portion of the substrate. The second resistiveelement provides a reference resistance for the flexure sensing device.

Yet another exemplary aspect of the present disclosure is directed to amethod for operating an appliance. The method can include monitoring astate of the appliance using a flexure sensing device. The flexuresensing device has a flexible portion and a non-flexible portion. Afirst resistive element can be formed on or within the flexible portion.The first resistive element can have a variable resistance dependent ona change in flexure of the flexible portion. The flexure sensing devicecan further include a second resistive element formed on or within thenon-flexible portion of the substrate. The second resistive element canprovide a reference resistance for the flexure sensing device. Themethod can further include detecting an output of the first resistiveelement and an output of the second resistive element of the flexuresensing device; determining a change in flexure of the substrate of theflexure sensing device based on the output of the first resistiveelement and the output of the second resistive element; and controllingthe appliance based on the determined change in flexure of the substrateof the flexure sensing device.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendedfigures, in which:

FIG. 1 depicts a perspective and longitudinal side view of an exemplaryflexure sensor according to an exemplary embodiment of the presentdisclosure;

FIG. 2 depicts a perspective view and a longitudinal side view of anexemplary flexure sensor according to an exemplary embodiment of thepresent disclosure;

FIG. 3 depicts a perspective view and a longitudinal side view of anexemplary flexure sensor according to an exemplary embodiment of thepresent disclosure;

FIG. 4 depicts a perspective view and a longitudinal side view of anexemplary flexure sensor according to an exemplary embodiment of thepresent disclosure;

FIG. 5 depicts a perspective view, a longitudinal side view, and ahorizontal side view of an exemplary flexure sensor according to anexemplary embodiment of the present disclosure;

FIG. 6 depicts a perspective view, a longitudinal side view, and ahorizontal side view of an exemplary flexure sensor according to anexemplary embodiment of the present disclosure;

FIG. 7 depicts a perspective view and a longitudinal side view of anexemplary flexure sensor according to an exemplary embodiment of thepresent disclosure;

FIG. 8 depicts a cross-sectional view of the exemplary flexure sensor ofFIG. 7 according to an exemplary embodiment of the present disclosure;

FIGS. 9-11 depict exemplary biasing networks used in conjunction withflexure sensors according to exemplary embodiments of the presentdisclosure;

FIG. 12 depicts a block diagram of an appliance control system accordingto an exemplary embodiment of the present disclosure;

FIG. 13 depicts a flow diagram of an exemplary method of controlling anappliance according to an exemplary embodiment of the presentdisclosure; and

FIG. 14 depicts a flow diagram of an exemplary method of manufacturing aflexure sensor device according to an exemplary embodiment of thepresent disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Reference now will be made in detail to embodiments of the invention,one or more examples of which are illustrated in the drawings. Eachexample is provided by way of explanation of the invention, notlimitation of the invention. In fact, it will be apparent to thoseskilled in the art that various modifications and variations can be madein the present invention without departing from the scope or spirit ofthe invention. For instance, features illustrated or described as partof one embodiment can be used with another embodiment to yield a stillfurther embodiment. Thus, it is intended that the present inventioncovers such modifications and variations as come within the scope of theappended claims and their equivalents.

Generally, the present disclosure is directed to a flexure sensor, and asystem and method of controlling an appliance using a flexure sensor.The sensor can include a substrate having a flexible portion and anon-flexible portion. A plurality of resistive elements, such as a firstresistive element and a second resistive element, can be disposed on orwithin the substrate. The first resistive element can have a variableresistance dependent on the flexure of the flexible portion. The secondresistive element can be disposed exclusively within the non-flexibleportion of the substrate. The second resistive element can provide areference resistance that can be used as part of a biasing network forthe flexure sensor.

In particular, the first resistive element can be formed on or withinthe flexible portion of the substrate such that the first resistiveelement is allowed to flex while the second element is constrained on orwithin the non-flexible portion of the substrate. This allows the secondresistive element to provide the reference resistance for biasing (e.g.as part of a bias network) the flexure sensor device. The referenceresistance, formed by the second resistive element within thenon-flexible portion of the flexure sensor, may be used as the “fixed”or “known” element of bias network, such as a simple two resistordivider network or within a Wheatstone Bridge network. Because thissecond resistance can be created using identical techniques andmaterials as the first resistance within the flexible portion of theflexure sensor, its nominal resistance tracks (matches) closely with theunflexed (relaxed, natural) state of the first resistance, and thetemperature coefficient of resistance (aka TCR) of the two resistiveelements also tracks (matches) closely. Thus, it can be seen that thetwo most problematic aspects of resistive flexure sensors are, for themost part, cancelled-out.

The sensor can be used within an appliance to detect various conditionssuch as temperature, moisture, air flow, etc. A change in condition canbe determined based on outputs of the resistive elements of the sensor.As the substrate flexes in response to changing conditions, the outputsof the first resistive element can be monitored for the change inresistance. The output of the second resistive element can be used tobias the output of the first resistive element such that the flexuresensor is self-calibrating.

The flexure sensor according to aspects of the present disclosure canprovide various advantages. For instance, any inconsistencies inmanufacturing resulting from the depositing of the first and secondresistive elements will be uniform across the resistive elements becausethe resistive elements can be formed on the substrate at the same time.In addition, any deterioration of tolerance and/or stability of theresistive elements over time would also be uniform because all theresistive elements are exposed to the same environmental conditionsthroughout the lifetime of the sensor. In addition, when the sensor iscoupled within a circuit for control, no additional circuitry elementsare needed to bias the sensor.

FIGS. 1-4 illustrate exemplary resistive flexure sensors 100 accordingto exemplary embodiments of the present disclosure. For instance, asshown in FIG. 1, the sensor 100 can include a substrate having aflexible portion 110 and a non-flexible portion 120. A first resistiveelement 130 can be disposed on or within the flexible portion 110 and asecond resistive element 140 can be disposed on or within thenon-flexible portion 120.

The flexible portion 110 of the substrate can include any electricallyinsulating material that is suitable as a substrate and is configured toretain form and shape while also being elastically flexible or bendable.For instance, the flexible material can be a plastic, resin, polymer,silicone, etc. (e.g. Kapton or polyimide film). The flexible materialcan also be a thin sheet of an electrically-conductive material (e.g.aluminum, steel, copper, etc.) which is then coated with anon-conductive layer (e.g. plastic, paint, etc.) prior to application ofthe resistive element material. Preferably, the flexible portion 110 ofthe substrate can flex without causing an electrical discontinuity oropen circuit in the first and/or second resistive elements 130, 140.

The non-flexible portion 120 can be formed from a substantially rigidmaterial that prevents flexing. For instance, the non-flexible portion120 can be a rigid material such as plastic, epoxy, bakelite, etc. Thenon-flexible portion 120 can be formed separately from the substrate andthen applied to the flexible portion 110 of the substrate. For instance,the non-flexible portion 120 can be injection molded and then coupled tothe flexible portion of the substrate, or even injection molded aroundthe flexible portion of the substrate (e.g. over-molded). Alternatively,the non-flexible portion 120 of the substrate can be formed by modifyinga portion of the flexible substrate 110.

When the non-flexible portion 120 of the substrate is formed separately,it can be coupled to the flexible portion 110 such that it surrounds aportion of the flexible portion 120 of the substrate as illustrated inFIG. 1. Alternatively, the non-flexible portion 120 can be coupled to atop surface of the substrate and/or a bottom surface of the substrate.For instance, as illustrated in FIG. 2, the non-flexible portion 120 canbe coupled to a surface opposite to the surface where the resistiveelements 130 and 140 are deposited.

A plurality of electrically resistive elements 130 and 140 can bedisposed on a surface of the substrate, such as a top or bottom surfaceof the substrate. The electrically resistive elements can be formed of amaterial that has electrical properties, including resistive properties.For instance, the electrically resistive elements 130 and 140 can be aconductive material, such as a conductive ink, deposited on thesubstrate using a silk-screen printing process such that the resistiveelements 130 and 140 are formed essentially simultaneously.

As shown in FIG. 1, the electrically resistive elements 130 and 140 canhave rectangular “U” shape. Alternatively, as shown in as shown in FIGS.3 and 4, the electrically resistive elements 130 and 140 can havenon-linear symmetrical shapes. The electrically resistive elements 130and 140 can have any shape, arrangement, and/or configuration. Forinstance, the electrically resistive elements 130 and 140 can have thesame shape or different shapes. The electrically resistive elements 130and 140 can also be continuous or segmented elements.

Referring back to FIG. 1, the first resistive element 130 havingconnectors 135 can be formed in both the flexible portion 110 and thenon-flexible portion 120 of the substrate. A second resistive element140 having connectors 145 can be formed exclusively within thenon-flexible portion 120. The sensor 100 can be mounted directly to aprinted circuit board (PCB) such that connectors 135 and 145 can beelectrically coupled to contacts in the PCB. This coupling of theresistive elements to the PCB can be accomplished by means of solderingthe connectors 135 and 145 into holes in the PCB, or by means ofinserting connectors 135 and 145 into a connector that has been solderedonto the PCB.

When conditions change causing the flexible portion 110 of the substrateto flex, the resistance of the first resistive element 130 changes andan output indicative of the change in flexure (i.e. a change involtage/current resulting from the change in resistance) is supplied tothe connectors 135. Since the second resistive element 140 isexclusively within the non-flexible portion 120 of the substrate, as thesubstrate flexes there should be substantially no change in theresistance of the second resistive element 140. For the purposes of thisapplication, “substantially no change” can include up to a 10% change inthe output indicative of the resistance of the second resistive element140. As a result, the second resistive element 140 can be used as areference resistance for the flexure sensor.

The second resistive element 140 can be formed from the same material asthe first resistive element 130 and can be formed on the same substrateas the first resistive element 130 using similar processing conditions.For example, the first resistive element 130 and the second resistiveelement 140 can be deposited on the substrate using a silk-screenprinting process such that the resistive elements 130 and 140 can beformed essentially simultaneously; a metal sputtering technique can alsobe used to simultaneously create the resistive elements. In this manner,the second resistive element 140 can provide improved biasing of theflexure sensor because it is subject to the same operatingcharacteristics and conditions as the first resistive element 130.

FIGS. 5 and 6 illustrate an exemplary flexure sensor 200 according toalternative exemplary embodiments of the present disclosure. Sensor 200can include a substrate having a flexible portion 210 and a non-flexibleportion 220. A first resistive element 230 providing an output throughterminal 235 can be disposed on or within the flexible portion 210. Asecond resistive element 240, providing an output through terminal 245can be disposed on or within the non-flexible portion 220.

A common conductive element 250 can be coupled between the firstresistive element 230 and the second resistive element 240 such that thecommon conductive element is deposited in both the flexible portion 210and the non-flexible portion 220 of the substrate. The common conductiveelement 250 can be coupled to terminal 255. The common conductiveelement 250 can have any shape, size, and/or configuration. In oneimplementation, the common conductive element 250 can be constructed ofa material whose resistance remains essentially unchanged with flexureof the flexible portion of the substrate. Ideally the common conductiveelement 250 is constructed of a material which offers very lowelectrical resistance, relative to the two flexure-sensitive resistiveelements.

As previously discussed, the resistive elements 230 and 240 can have anyshape, size, and/or configuration. For instance, as shown in FIGS. 5 and6, the widths of the first resistive element 230 and the secondresistive element 240 can also be variable. More particularly, in FIG.5, the widths of the first resistive element 230 and the secondresistive element 240 are essentially the same. As a result, therelative resistances of the first resistive element 230 and the secondresistive element 240 are different based on the ratio of their lengths.In FIG. 6, the width of the longer first resistive element 230 isgreater (wider) than the width of the shorter second resistive element240. As a result, the resistances of the first resistive element 230 andthe second resistive element 240 can be made nearly identical. Anyresistance ratio (in the non-flexed condition) can be achieved usingthese geometric scaling techniques.

The sensor 200 can be mounted in a PCB using mounting pins 225 where themounting pins 225 can be non-conductive. In addition, outputs 235, 245of the resistive elements 230 and 240, and the output 255 of the commonconductive element 250 can be electrically coupled to contacts in thePCB.

FIGS. 7 and 8 illustrate an exemplary flexure sensor 300 according toanother exemplary embodiment of the present disclosure. Specifically,FIG. 7 depicts a perspective view of the sensor 300 and FIG. 8 depicts across-sectional view of the sensor 300. The flexure sensor 300 caninclude a substrate having a flexible portion 310 and a non-flexibleportion 320. A first resistive element 330 providing an output throughterminals 335 can be disposed on or within the flexible portion 310. Asecond resistive element 340 providing an output through terminals 345can be disposed on or within the non-flexible portion 310.

As illustrated in FIG. 8, the first resistive element 330 and flexibleportion 310 can provided between encapsulation layers 315 and 325. Theencapsulation layers 315 and 325 can be made of any material that wouldprotect the sensor 300 from degradation and/or malfunction. Forinstance, the encapsulation layers 315 and 325 can prevent the resistiveelements 330 and 340 from premature erosion. In addition, theencapsulation layers 315 and 325 can prevent unwanted moisture frompermeating the sensor.

FIGS. 9-11 illustrate the use of an exemplary flexure sensor 400 inconjunction with various bias networks according to exemplaryembodiments of the present disclosure. In particular, FIG. 9 depicts theexemplary flexure sensor 400 used as part of a simple two resistordivider network. More particularly, the flexure sensor 400 includes afirst resistive element 420 located on or within a flexible portion ofthe substrate a second resistive element 440 located on or within anon-flexible portion of the substrate. The first resistive element 420and the second resistive element 440 can form a simple two resistordivider network. The second resistive element 440 acts as the referenceresistance for the flexure sensor 400. A common terminal 455 coupledbetween the first resistive element 420 and the second resistive element440 can provide an output V_(flex) signal (across e.g. capacitor C1) asthe output of the flexure sensor 400.

FIG. 10 depicts the exemplary flexure sensor 400 used as part of aWheatstone Bridge configuration. In particular, the first resistiveelement 420 and the second resistive element 440 are used in conjunctionwith resistors R1 and R2 to provide a Wheatstone Bridge. The secondresistive element 440 acts a reference resistance for the flexure sensordevice. In this arrangement, the common terminal 455 and a node 457between resistors R1 and R2 are coupled as inputs to a suitableamplifier circuit 460. The output of the amplifier circuit 460 providesoutput V_(flex) as the output of the flexure sensor 400.

FIG. 11 depicts the exemplary flexure sensor 400 used as part of aresistance to voltage converter bias network. Similar to FIGS. 9 and 10,the flexure sensor 400 includes a first resistive element 420 located onor within a flexible portion of the substrate a second resistive element440 located on or within a non-flexible portion of the substrate. Thesecond resistive element 440 acts as a reference resistance for theflexure sensor 400. In the arrangement of FIG. 11, the common terminal455 of the flexure sensor 400 as well a constant voltage V_(s) areprovided to an amplifier circuit 460. The output of the amplifiercircuit 460 provides output V_(flex) as the output of the flexure sensor400. The output V_(flex) is also used as a feedback coupled to thesecond resistive element 440.

FIGS. 9-11 illustrate exemplary bias network configurations for purposesof illustration and discussion. Those of ordinary skill in the art,using the disclosures provided herein, should understand that anysuitable bias network configuration can be used without deviation fromthe scope of the present disclosure.

FIG. 12 illustrates a block diagram of an appliance control system 500according to an exemplary embodiment of the present disclosure. System500 can include a flexure sensing device 510, a controller 520, and asubsystem of the appliance 530.

System 500 can be used in any appliance in which a condition can bemonitored using flexure sensing device 510 such as a refrigerator, anoven, an HVAC unit, an air conditioner, a clothes dryer, an airconditioner, a space heater, a dehumidifier, a humidifier, a range hood,a bathroom fan, a furnace, etc. For instance, the flexure sensing device410 can be disposed to detect air flow in the cooling pathway of anoven, with the controller configured to disable the heating elements ofthe oven if the detected air flow is insufficient. Alternatively, theflexure sensing device 510 can be disposed in a compressor of arefrigerator to detect, with the controller configured to disable thecompressor if the detected moisture level is too great.

Controller 520 can monitor the output of the flexure sensing device 410and control the appliance accordingly. For instance, the controller 420can monitor the output of a first electrically resistive element of theflexure sensing device 410 and the output of a second electricallyresistive element of the same flexure sensing device to determine acalibrated output of the sensing device 410 based on a differencebetween the output of the first electrically resistive element and thesecond electrically resistive element.

The controller 520 can be positioned in any location in the appliance.In addition, when controller 520 is a single controller it can be theonly controller in the appliance such that controller 520 controls alloperations of the appliance. Alternatively, when the appliance includesa plurality of controllers, controller 420 can be a sub-controllercoupled to the overall appliance controller or it could be the overallappliance controller. If controller 520 is a sub-controller, it can belocated with the overall appliance controller or be separate from theoverall appliance controller.

By way of example, any/all of the “controllers” discussed in thisdisclosure, may include a memory and one or more processing devices suchas microprocessors, CPUs or the like, such as general or special purposemicroprocessors operable to execute programming instructions ormicro-control code associated with operation of an appliance. The memorymay represent random access memory such as DRAM, or read only memorysuch as ROM or FLASH. In one embodiment, the processor executesprogramming instructions stored in memory. The memory may be a separatecomponent from the processor or may be included onboard within theprocessor. Alternatively, the controller might also be constructedwithout using a microprocessor, using a combination of discrete analogand/or digital logic circuitry (such as amplifiers, integrators,comparators, flip-flops, AND gates, and the like) to perform the ovencontrol functionality instead of relying upon software.

In a particular embodiment of the present disclosure, the flexuresensing device 510 can be implemented to monitor a condition present inan appliance. Controller 520 can monitor the output of the flexuresensing device 510. When a change in the condition causes the flexuresensing device to flex, the controller 520 can detect the resistance ofa first resistance element and the second resistance element. Thecontroller 520 can determine a difference between the resistancedetected at the first resistance element and the second resistanceelement to determine a change in the flexure of the substrate. Thedifference can be compared to a predetermined threshold where thepredetermined threshold can be a predetermined range or value. When thedifference exceeds or falls below the predetermined threshold, thecontroller 520 can control a subsystem of the appliance 530.

Alternatively, the difference between the detected resistance of thefirst resistance element and the second resistance element can becompared to a look-up table, algorithm, equation, or model to determinea magnitude of the change in flexure of the substrate. The controller520 can variably control the subsystem of the appliance based on themagnitude of the change in flexure of the substrate.

For example, when the appliance is an oven and the flexure sensingdevice 510 is disposed within an air duct of the oven to monitor the airflow, the system 500 can perform as follows. The flexure sensing device510 can be mounted to a PCB in the air duct and be configured to monitorthe air flow in the air duct. As the air flow causes the sensing device510 to flex, the resistance of the first resistive element and thesecond resistive element are measured. The controller 420 can determinethe rate of air flow in the air duct based on the outputs of the firstresistive element and the second resistive element. The differencebetween the detected resistances of the resistive elements cancorrespond to a change in flexure of the substrate. The change inflexure of the substrate can correspond to a predetermined air flow.When the detected air flow falls below a predetermined air flowthreshold, the controller 520 can deactivate a subsystem of the oven,such as the heating element, to prevent overheating.

FIG. 11 illustrates a flow chart of exemplary method (600) according toan exemplary embodiment of the present disclosure. The method (600) canbe implemented with any suitable appliance having a flexure sensingdevice, such as the flexure sensing devices illustrated in FIGS. 1-8. Inaddition, although FIG. 11 depicts steps performed in a particular orderfor purposes of illustration and discussion, the methods discussedherein are not limited to any particular order or arrangement. Oneskilled in the art, using the disclosures provided herein, willappreciate that various steps of the methods can be omitted, rearranged,combined and/or adapted in various ways.

At (610) an output of a first electrically resistive element can bedetected and at (620) an output of a second electrically resistiveelement can be detected. The difference between the first electricallyresistive element and the second electrically resistive element can bedetermined at (620). The difference between the outputs can be used todetermine a change in the flexure of the sensor at (630). For instance,the difference between the outputs can be compared to a predeterminedthreshold and when the difference exceeds the threshold, a look-uptable, algorithm, equation, and/or model can be used to determine amagnitude of the change in sensor flexure at (640). Based on themagnitude of the change in flexure, a subsystem of the appliance can becontrolled at (650). In an alternative embodiment, the subsystem can becontrolled based solely on the difference between the outputs withouthaving to determine the magnitude of the change in flexure.

FIG. 14 illustrates a flow chart of exemplary method (700) ofmanufacturing a flexure sensor according to an exemplary embodiment ofthe present disclosure. At (710), a flexible substrate can be provided.The flexible portion of the substrate can include any electricallyinsulating material that is suitable as a substrate and configured toretain form and shape while also being elastically flexible or bendable.For instance, the flexible material can be a resin, polymer, silicone,etc.

At (720), the method can include depositing the first and secondresistive elements on the flexible substrate. For instance, theresistive elements deposited on the substrate using a silk-screenprinting process such that the electrically resistive elements and areformed simultaneously. As shown at (730), a common element coupling thefirst and second electrically resistive elements can also be formed onthe flexible substrate. The common element can be formed simultaneouslywith or separate from the first and second electrically resistiveelements.

At (740), the method includes forming a non-flexible portion of thesubstrate such that the second resistive element is disposed within thenon-flexible portion of the substrate. The non-flexible portion can beformed from a substantially rigid material that prevents flexing. Forinstance, the non-flexible portion can be a rigid material such asplastic, epoxy, bakelite, etc.

In one particular implementation, the non-flexible portion can be formedseparately from the substrate and then applied to the flexible portionof the substrate. For instance, the non-flexible portion 120 can beinjection molded and then coupled to the flexible portion of thesubstrate. Alternatively, the non-flexible portion of the substrate canbe formed by modifying a portion of the flexible substrate. When thenon-flexible portion of the substrate is formed separately, it can becoupled to the flexible portion such that it surrounds a portion of theflexible substrate. Alternatively, the non-flexible portion can becoupled to a top surface of the substrate and/or a bottom surface of thesubstrate.

Finally, the method can include depositing encapsulation layers on thesubstrate (750). The encapsulation layers can cover one or more portionsof the substrate, such as the flexible portion and/or the non-flexibleportion. The encapsulation layers can prevent the resistive elementsfrom premature erosion. In addition, the encapsulation layers canprevent unwanted moisture from permeating the sensor. The material usedfor the encapsulation layers can be flexible so as to not impede theflexure of the flexible portion of the sensor.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they include structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

What is claimed is:
 1. A flexure sensing device comprising: a substratehaving a flexible portion and a non-flexible portion; a firstelectrically resistive element formed on or within the flexible portionof the substrate, the first electrically resistive element having avariable electrical resistance dependent on a change in flexure of theflexible portion of the substrate; and a second electrically resistiveelement formed on or within the non-flexible portion of the substrate,the second electrically resistive element providing a referenceresistance for biasing the flexure sensing device such that thereference resistance provides a fixed resistive element of a biasnetwork; and a common conductor coupled between the first electricallyresistive element and the second electrically resistive element, thecommon conductor formed on or within both the flexible portion of thesubstrate and on or within the non-flexible portion of the substrate; afirst terminal connected to the first electrically resistive element, asecond terminal connected to the second electrically resistive element,and a third terminal connected to the common conductor, the firstterminal, second terminal, and third terminal being configured to beelectrically coupled to contacts in a printed circuit board (PCB);wherein the non-flexible portion of the substrate surrounds at least aportion of the flexible portion of the substrate.
 2. The device as inclaim 1, wherein the second electrically resistive element is disposedexclusively on or within the non-flexible portion of the substrate. 3.The device as in claim 1, wherein the second electrically resistiveelement is constructed using the same material and in essentially thesame manner as the first electrically resistive element.
 4. The deviceas in claim 1, wherein the device comprises one or more encapsulationlayers disposed on at least one of the flexible portion or thenon-flexible portion.